Design a product notifications system

Q: Design a product notifications system

This question evaluates system design competencies for building a large-scale notifications platform—covering architecture, APIs, data modeling, event pipelines, delivery semantics (retries, deduplication, idempotency), targeting/segmentation, localization, monitoring, and legal compliance such as GDPR/CCPA.

Q: How do I approach System Design interview questions?

System Design questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master system design interviews.

Q: What difficulty level is this interview question?

This is a hard difficulty System Design question, commonly asked during Onsite rounds at Meta.

Q: What role is this question designed for?

This question is commonly asked for Software Engineer candidates at Meta during technical interviews.

Question

System Design: Push Notifications and In‑App Messaging Platform

Context

Design a notifications platform for a large consumer mobile app with millions of daily active users. The platform must support both push notifications (iOS/Android) and in‑app messaging, with rich targeting, personalization, and compliance.

Functional Requirements

User preferences and consent
- Channels: push, in‑app (future‑proof for email/SMS)
- Topics/categories, frequency caps
- Quiet hours and time zone handling
Segmentation and targeting
- Dynamic segments, real‑time triggers, and scheduled campaigns
Deduplication
- Across retries and overlapping campaigns; vendor collapse keys
Rate limiting and throttling
- Per user, per campaign, and global/vendor limits
Retries, backoff, and idempotency
Scheduling and batching
- Future send times and batching for efficiency
A/B experiments
- Randomized assignment, holdouts, metrics
Localization
- Templates, placeholders, pluralization, fallbacks
In‑app messaging
- Message inbox, triggers, display rules, and impression tracking

System Requirements

Describe APIs, data model, event pipeline, delivery workers
Integrate with APNs (iOS) and FCM (Android)
Scale to millions of DAUs and bursty traffic
Multi‑region deployment and CAP trade‑offs
Monitoring, alerting, and SLOs
GDPR/CCPA compliance
Failure handling and graceful degradation
Capacity estimates and a safe rollout plan

Design a product notifications system

Quick Overview

System Design: Push Notifications and In‑App Messaging Platform

Context

Functional Requirements

System Requirements

Solution

Comments (0)